All the current floorstanding range seems to be 3 way instead of 2 way like the 5-series. I don’t know if sonically there are any differences between the models.
The 580 is a two way with a compression driver, while the 280 is a three way and doesn’t. It’d be a shame if the 280 were a replacement for the 580, it seems much more boring.
It’s not the number of ways, it’s the compression driver. I’m partial to a JBL compression driver - indeed I have five pairs in my two main sets of speakers